Ahhh, the Holleys are a piece of cake.
Are the outside dueces operated mechanically or by vacuum?
In either setup, adjusting the outside dueces to open and close at the same time is pretty simple.
They are tied together by a single actuator rod. The connection point to each carb at the ends of the rod is adjustable. You job,..should you accept it,..is to make sure the carbs are fully closed at idle. To do this, remove the common actuator rod and manully flex the butterflies on each carb. Let them snap closed from about 1/2 open. This insures they are fully closed.
When you reinstall the actuator rod, be sure to adjust the rod so there is but a ever so slight pressure pulling the butterfly on each carb. Because of the rods length, when it gets hot it lengthens, the slight pressure will then relax on the butterflies.
Rebuilding them is a snap. They are pretty simple and straighforward, just be sure to check the floats and float levels. Take a can of gas and drop the floats in it. They should all sit about the same height. If one or more are much lower than the others, replace them.
Make sure the floats are setting at the right height in the carb tank. Some of the Holleys required you to bend a tab on the float for adjustment, some had adjustment screws. If yours require bending the tab, be gentle. The tab is spring steel and hard to bend. Grab a pair of pliers, or a small vise and use that to hold the floats bracket while bending the tab.
If the carbs have been setting long, be sure to clear the idle jets. They had a tendency to varish up after sitting for long periods of time. Gas won't cut through the varnish. Get some carb cleaner from your local auto parts store.
Use a toothpick to clear passages. It won't harm the soft brass jets. Be careful not to break it off in the carb though

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Hope this helps,...wtg on that map.
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Roy "Skuzzy" Neese
President, AppLink Corp.
http://www.applink.netskuzzy@applink.net